1. Field of the Invention
The present invention relates to a manufacturing apparatus of a semiconductor device having an introducing section and withdrawing section, particularly relates to a layout of manufacturing apparatuses of a semiconductor device, which permits improving the transfer efficiency of a semiconductor article within a clean room.
2. Description of the Related Art
In the manufacturing process of a semiconductor device, semiconductor substrates are handled in general in a supervising unit called a lot consisting of 13 semiconductor substrates or 24 or 25 semiconductor substrates. Also, the semiconductor substrates handled in a unit of a lot are housed in a semiconductor substrate housing container called a carrier. In a clean room in which the semiconductor device is actually manufactured, the semiconductor substrates, which are set in a cassette or a carrier, are housed in a semiconductor substrate transfer box so as to be transferred and stored.
There are several methods of introducing the semiconductor substrates, which are supervised as described above, into a manufacturing apparatus of a semiconductor device, hereinafter referred to simply as “a manufacturing apparatus”, arranged within the clean room, as summarized below:
(1) A cassette housing the semiconductor substrates is taken out of the transfer box so as to be set in the manufacturing apparatus.
(2) The transfer box housing the semiconductor substrates are set in the manufacturing apparatus, with the lid of the transfer box left open.
(3) The transfer box housing the semiconductor substrates are set in the manufacturing apparatus, with the lid of the transfer box kept closed.
In methods (1) and (2) given above, required is a manual operation performed by the operator in taking out the cassette from the transfer box and in opening the lid of the transfer box. The particular cassette is called an open cassette.
On the other hand, method (3) given above does not require a manual operation, and the semiconductor substrate is automatically taken in by the manufacturing apparatus. For example, the manufacturing apparatus automatically opens the lid of the transfer box so as to take in the semiconductor substrate. Alternatively, if the transfer box is set in the manufacturing apparatus, the manufacturing apparatus takes in the transfer box itself and opens the lid of the transfer box inside the manufacturing apparatus so as to take out the semiconductor substrate from the cassette.
The layout of the particular manufacturing apparatuses within a clean room will now be described with reference to FIG. 1 showing a partial region of the clean room.
As shown in the drawing, a clean room 100 includes a utility area 120 and a working area 130. The utility area 120 is partitioned from the working area 130 by a wall, and various manufacturing apparatuses 110-1 to 110-14 are arranged within the utility area 120. The working area 130, which is the region other than the utility area 120, has a cleanliness higher than that of the utility area 120. A semiconductor substrate introducing section (loader section) 111 and a semiconductor substrate withdrawing section (unloader section) 112 are included in each of the manufacturing apparatuses 110-1 to 110-14. The semiconductor substrate is introduced into the manufacturing apparatus through the semiconductor substrate introducing section 111, and is withdrawn from the manufacturing apparatus through the semiconductor substrate withdrawing section 112. Only these introducing section 111 and withdrawing section 112 extend from the utility area 120 so as to be exposed to the working area 130. The transfer of each semiconductor substrate and, in some cases, various manual operations are carried out within the working area 130.
As described above, the clean room is partitioned in general into a region requiring a high cleanliness (working area) and another region that does not require a high cleanliness (utility area).
If manufacturing apparatuses are to be efficiently installed within a clean room which is partitioned into a plurality of regions based on the required cleanliness, the manufacturing apparatuses 110-1 to 110-14 are to be arranged side by side as shown in FIG. 1. In this case, the working area 130 is in the form of a passageway.
There are two methods of handling the semiconductor substrates before and after the processing, as summarized below:
(1) The semiconductor substrates, which are housed in a certain cassette before the processing, are housed in another cassette after the processing.
(2) The semiconductor substrates after the processing are housed in the cassette previously used for housing the semiconductor substrates before the processing.
Which of the methods (1) and (2) given above to employ is determined by the specification of the manufacturing apparatus and by the layout of the clean room in which the manufacturing apparatuses are installed and the operating policy of the clean room.
Where the semiconductor substrates after the processing are not brought back to the cassette housing the semiconductor substrates before the processing as in method (1) given above, the semiconductor substrate introducing section and the semiconductor substrate withdrawing section are arranged to form a pair on the front surface of the manufacturing apparatus, as shown in FIG. 1.
Where the semiconductor substrates after the processing are housed in the cassette housing the semiconductor substrates before the processing as in method (2) given above, it is possible for a single section to act both as a semiconductor substrate introducing section and as a semiconductor substrate withdrawing section. The cassette in which the same semiconductor substrates are set both before and after the processing is generally called a uni-cassette. To be more specific, at least one section acting both as a semiconductor substrate introducing section and as a semiconductor substrate withdrawing section is formed in the front surface of the manufacturing apparatus that is operated by using a uni-cassette. Incidentally, in the case of using a uni-cassette, the same transfer box housing the cassette is used in general both before and after the processing of the semiconductor substrate.
However, above-noted methods (1) and (2) for handling the semiconductor substrate both before and after the processing of the semiconductor substrate are advantageous in some respects and disadvantageous in other respects, making it difficult to determine which method is the best method.
First of all, method (1), in which the semiconductor substrates after the processing are not brought back to the cassette previously housing the semiconductor substrates before the processing, will now be described with reference to FIG. 1. The arrows of the solid lines shown in FIG. 1 denote the flow of the transfer box housing the semiconductor substrates, and the arrows of the broken lines denote the flow of the vacant transfer box. Suppose, for example, that the semiconductor substrate is processed in the manufacturing apparatuses 110-12, 110-3 and 110-4 in the order mentioned.
In the first step, the transfer box housing the semiconductor substrate processed in the manufacturing apparatus 110-12 is set in the semiconductor substrate introducing section 111 of the manufacturing apparatus 110-3. Also, a vacant transfer box is set in the semiconductor substrate withdrawing section 112 of the manufacturing apparatus 110-3. In the manufacturing apparatus 110-3, a prescribed processing is applied to the semiconductor substrate housed in the transfer box set in the semiconductor substrate introducing section 111. After completion of the processing, the processed semiconductor substrate is housed in the vacant transfer box set in the semiconductor substrate withdrawing section 112. The transfer box housing the processed semiconductor substrate is set in the semiconductor substrate introducing section 111 of the next manufacturing apparatus 110-4.
On the other hand, the transfer box set in the semiconductor substrate introducing section 111 of the manufacturing apparatus 110-3 becomes vacant. The vacant transfer box is set again in the semiconductor substrate withdrawing section 112 of, for example, the manufacturing apparatus 110-12 used for applying the previous processing to the semiconductor substrate. In this case, the transfer box reciprocating between the manufacturing apparatus 110-12 and the manufacturing apparatus 110-3 is allowed to maintain the same cleanliness. Also, the transfer box that has been become vacant provides a transfer box for receiving the next semiconductor substrate and, thus, is transferred to another process step. Alternatively, it is possible for the vacant transfer box to be washed and, then, transferred for receiving the next semiconductor substrate. In this case, the semiconductor substrate after the processing is housed in a new transfer box. It follows that the semiconductor substrate is not contaminated within the transfer box. Naturally, the cleanliness of the semiconductor substrate is not impaired.
However, in the handling method of the semiconductor substrate described above, problems are generated that the efficiency of the cleanliness supervision of the entire clean room becomes poor, and that the operation and supervision of the transfer box become troublesome. To be more specific, the cleanliness required for the transfer box differs depending on the process steps. For example, the semiconductor substrate in the process step falling within a range of between the etching step and the resist removing step is coated with a resist film. Therefore, it suffices for the cleanliness of the transfer box for transferring the semiconductor substrate between the process steps falling within the range noted above to be relatively low. On the other hand, the transfer box used in the steps falling within a range of between the cleaning step and the film-deposition step requires a very high cleanliness.
In the case of the layout of the manufacturing apparatuses as shown in FIG. 1, moved within the working area 130 are the semiconductor substrate which is to be maintained at a high cleanliness, the semiconductor substrate to which are attached a resist material and a reactive gas, the transfer box storing the semiconductor substrate, the cassette, and the vacant transfer box. Since the transfer boxes differing from each other in the cleanliness are moved within the same site, it is difficult to supervise efficiently the cleanliness of the clean room. Further, since the transfer boxes having various degrees of cleanliness are present within the working area 130, the operation and supervision of the working area 130 become troublesome and complex.
It should also be noted that it is necessary to put in the transfer box a supervising tag indicating the information on the semiconductor substrate housed in the transfer box and the information on the present process stage of the semiconductor substrate. In the case of method (1), the transfer box is replaced every time the processing performed in the manufacturing apparatus. Therefore, it is necessary to transfer the supervising tag put in the semiconductor substrate introducing section into the transfer box positioned in the semiconductor substrate withdrawing section. It follows that the supervision of the transfer box become troublesome in this respect, too.
On the other hand, in the case of method (2) using a uni-cassette, the semiconductor substrate processed in the manufacturing apparatus is brought back into the transfer box previously housing the semiconductor substrate before the processing. It follows that the transfer box does not become vacant, with the result that the supervision of the transfer box can be simplified and, at the same time, the problem relating to the supervising tag can be solved.
However, in the case of using a uni-cassette, a new problem is generated that it is difficult to maintain the cleanliness within the transfer box. For example, the semiconductor substrate after the lithography process is coated with a resist film, with the result that it is possible for the resist to be attached to the cassette. Further, suppose that an etching treatment is performed in, for example, a dry etching apparatus in the next step. In this case, the cassette adsorbs the reactive gas attached to the semiconductor substrate and released from the semiconductor substrate in the dry etching step. It follows that, if various processes are performed successively, the chemical solution, the gas, etc., used in the processing are attached to the transfer box every time the processing is performed.
The contamination of the transfer box noted above is a serious problem. Even if the semiconductor substrate is cleansed by removing the resist from the semiconductor substrate and by washing the semiconductor substrate, the cleanliness of the semiconductor substrate becomes poor because the inner region of the transfer box is contaminated with the resist or the reactive gas. In this fashion, the use of a uni-cassette gives rise to the problem that the transfer box and the cassette are contaminated with progress of the processing, and the semiconductor substrate is also contaminated in accordance with contamination of the transfer box and the cassette.
The conventional layout of another manufacturing apparatuses in a clean room will now be described with reference to FIG. 2.
As shown in the drawing, the working area within the clean room 100 is divided into three working areas 130-1, 130-2 and 1303 depending on the cleanliness required for the transfer box. Also, the kinds of the manufacturing apparatuses that are to be installed in the utility areas 120-1 to 120-4 are determined in accordance with the cleanliness of the working area. Further, the transfer boxes are classified depending on the cleanliness thereof into a transfer box to which resist is attached, a transfer box of a low cleanliness to which is attached a gas in, for example, the etching process, and a transfer box of a high cleanliness used in the film-deposition processing and requiring a very high cleanliness. It should be noted that the working areas 130-1 to 130-3 provide a zone in which are moved the transfer boxes having various degrees of the cleanliness noted above.
In the case of the clean room of the construction described above, only the transfer boxes having substantially the same cleanliness are moved within each working area so as to facilitate the supervision of the cleanliness within the clean room and the operation and supervision of the transfer box. On the other hand, where the transfer box is transferred between the working areas differing from each other in the level of the cleanliness, the transfer distance becomes long. At the same time, the transfer of the transfer box becomes highly complex, with the result that it is difficult to supervise the transfer box.
In the method using a uni-cassette, the problem referred to above remains unsolved even if the layout of the clean room is changed.
In conclusion, it is very difficult to maintain the required cleanliness of the semiconductor substrate by the apparatus construction of the uni-cassette alone. Under the circumstances, it is necessary to use an exclusive apparatus equipped with a replacing mechanism for replacing the transfer box and the cassette for maintaining the required cleanliness or a manufacturing apparatus equipped with a mechanism including a semiconductor substrate introducing-withdrawing section and replacing the transfer box before and after the processing. However, if the transfer box is transferred by introducing these apparatuses, the transfer of the transfer box housing the semiconductor substrate and the vacant transfer box becomes highly complex.
As described above, if the semiconductor substrate is transferred by using a uni-cassette in the conventional manufacturing apparatus and the manufacturing system of the semiconductor device, it is possible to obtain the merit that the transferring supervision of the transfer box is facilitated and the supervising tag need not be moved. However, the conventional technology gives rise to the problem that it is difficult to maintain the required cleanliness of the semiconductor substrate because the inner region of the transfer box is contaminated every time the processing is performed.
Also, in the system in which the semiconductor substrate after the processing is housed in a transfer box differing from the transfer box housing previously the semiconductor substrate before the processing, the required cleanliness within the transfer box can be maintained easily. In this case, however, it is necessary to move the supervising tag every time the processing is performed within the manufacturing apparatus. Also, the transferring route of the transfer box becomes complex. As a result, a problem is generated that the supervision in the cleanliness of the clean room and the transferring supervision of the transfer box become complex and difficult.